The active-clamp couple-buck converter-a novel high efficiency voltage regulator modules

As the power demand for microprocessors increases steadily, the VRMs are required to work with a higher input voltage. The widely used synchronous buck converter will NOT work properly and efficiently for this higher input voltage because of an extremely small duty-ratio, This paper proposes a novel active-clamp couple-buck converter to solve the extremely small duty-ratio problem, Other benefits of the proposed circuit include recovery leakage energy, clamped device voltage and reduced input filter. The proposed circuit was demonstrated on a 4-phase VRM, which delivers power from a 12 V input to a 1.5 V/50 A microprocessor load. Experiments show that the proposed circuit would significantly improve the VRM efficiency.